1. Slice the tomatoes.

2. Roughly chop the basil leaves.

3. In a bowl, combine the tomatoes, basil, chopped onion, and grated gouda.

4. Drizzle with extra-virgin olive oil and season with salt and pepper.

5. Gently toss to evenly distribute all the ingredients.

6. Chill in the refrigerator for at least 30 minutes.

7. Garnish with hard-boiled eggs before serving.